The present invention relates to a non-contact power supply system and apparatus for supplying electric power to a load from a feeder line connected to an AC power source via a pickup portion magneto-coupled in a physically non-contact state with the feeder line, and to carrying equipment using the non-contact power supply system and apparatus.
In general, a monorail type carrying equipment has been widely employed in an assembly process of an automobile or the like. In such carrying equipment, a plurality of carrier vehicles, on which an assembly part to be carried is placed, are put on a common rail, and feeding is carried out with respect to a drive motor and a control system mounted on each carrier vehicle so that each carrier vehicle is independently driven and controlled, and thus, each carrier vehicle is automatically driven while being stopped at each predetermined station.
As one of power supply methods with respect to each carrier vehicle, a non-contact power supply apparatus is employed. More specifically, in the non-contact power supply apparatus, a feeder line connected to an AC power source is arranged along a common rail, and a carrier vehicle side is provided with a pickup portion magneto-coupled in a physically non-contact state with the feeder line, and thus, power supply is carried out with respect to each carrier vehicle from the feeder line via the pickup portion.
Non-contact power supply apparatus in the prior art, as shown in FIG. 1 and FIG. 2 has been known. FIG. 1 is a schematic view showing a construction of a parallel resonance non-contact power supply apparatus, and FIG. 2 is a schematic view showing a construction of a general serial resonance non-contact power supply apparatus.
In FIG. 1, a reference numeral 5 denotes a magnetocoupling portion, and 6 denotes an incoming circuit. The magnetocoupling portion 5 comprises a feeder line 2 connected to a high-frequency AC power source and a pickup portion 10, and the feeder line 2 and the pickup portion 10 are magneto-coupled in a physically non-contact state. The pickup portion 10 comprises a pickup core 11 made of a magnetic body and a pickup coil 12 wound around the core 11. The incoming circuit 6 is composed of a resonance capacitor 21 which is connected in parallel with both ends of the pickup coil 12 of the pickup portion 10, a constant-current/constant-voltage converting part 22 and a rectifying part 23. A load such as a drive motor (not shown) of a carrier vehicle is connected to the rectifying part 23 of the incoming circuit 6.
In the aforesaid parallel resonance non-contact power supply apparatus, when a constant current of about 10 to 20 kHz flows to the feeder line 2 from the AC power source, a magnetic flux generated around the feeder line 2 is interlinked with the pickup coil 12 of the pickup portion 10 in the magneto-coupled portion 5, and thus, an induced power is generated in the pickup coil 12. An inductance of the pickup coil 12 and a capacitance of the resonance capacitor 21 are set so as to have a resonance relation, and thereby, these pickup coil 12 and the resonance capacitor 21 function as a constant current source. Then, the generated induced power is converted into a constant voltage as a predetermined constant current by means of the constant-current/constant-voltage converting part 22, of the incoming circuit 6 and further, is rectified by means of the rectifying part 23, and thus, is supplied to a load.
On the other hand, in the serial circuit as shown in FIG. 2, the resonance capacitor 21 is connected in series to the pickup coil 12, and the incoming circuit 6 is composed of a rectifying part 23 which is provided with a load
In the aforesaid serial resonance non-contact power supply apparatus, when a constant current of about 10 to 20 kHz flows to the feeder line 2 from the AC power source, a magnetic flux generated around the feeder line 2 is interlinked with the pickup coil 12 of the pickup portion 10 in the magnetocoupling portion 5, and thus, an induced power is generated in the pickup coil 12. An inductance of the pickup coil 12 and a capacitance of the resonance capacitor 21 are set so as to have a resonance relation, and thereby, these pickup coil 12 and the resonance capacitor 21 function as a constant voltage source. Then, the generated induced power is rectified as a predetermined constant voltage by means of the rectifying part 23 of the incoming circuit 6, and then, is supplied to a load.
In the aforesaid parallel resonance non-contact power supply apparatus, even in the case where no load is operated, a large circulating current flows through a resonance circuit comprising the pickup coil 12 and the resonance capacitor 21, and then, the pickup coil 12, which is a secondary winding, is exothermic. For this reason, a supply of current must be carried out with respect to a load within a coating heat-proof limit range of the pickup coil 12; as a result, there is a problem that a supply capability is limited. Further, there is a problem that the constant-current/constant-voltage converting part 22 is indispensable to the incoming circuit 6.
On the other hand, in the serial resonance non-contact power supply apparatus, a constant voltage source is composed of a resonance circuit comprising the pickup portion 10 and the resonance capacitor 21; therefore, no converter circuit for constant-current and constant-voltage is required. A current flowing through the pickup coil 12 is small as a load current; however, there is an air gap between distal ends of the pickup core 11 of the magnetocoupling portion 5; for this reason, a mutual inductance between the feeder line 2 and the pickup portion 10 is small. In order to supply a required voltage to a load, the number of windings of the pickup coil 12 must be increased. As a result, an inductance of the pickup coil 12 becomes large, and in the case where a current flows through the load, a potential difference between both terminals of the pickup coil 12 becomes several thousands of voltages. Thus, a discharge is generated between adjacent windings; as a result, there is the possibility that a dielectric breakdown is caused. Further, like the case of the aforesaid parallel resonance non-contact power supply apparatus, there is a problem in that a supply capability must be limited.